1. Field of the Invention
The present invention relates to generally to a rotator, which is connected with and driven by an endless cord member, for use in a window blind for driving a roller around which a blind shade is wound, and more particularly to such a cord-driven rotator, which has a cord member clamping function that prevents the cord member from slipping relative to the rotator.
2. Description of the Related Art
A conventional cord-driven rotator for use in a lifting window blind or the like is known comprising a base, which has a shaft, a friction wheel, which is pivoted to the shaft and has a V-shaped groove extended around the periphery, and an axle sleeve sleeved onto the shaft and connected between the friction wheel and the roller for synchronous rotation with the friction wheel on the shaft for driving the roller of the lifting window blind. The endless lift cord of the lifting window blind is hung in the V-shaped groove of the friction wheel and extended around the periphery of the upper half of the friction wheel. When pulling the lift cord, the friction wheel is driven by the lift cord to rotate the axle sleeve on the shaft, thereby causing the roller of the lifting window blind to rotate and to further lift or lower the blind shade that is connected to the roller. The V-shaped groove receives the lift cord, preventing slipping of the lift cord. In an alternative design of the conventional cord-driven rotator, the friction wheel is made having recessed round holes in two opposite sides thereof adjacent to the V-shaped groove for accommodating the beads of a lift cord formed of a chain of beads. However, because the pitch between each two adjacent recessed round holes is fixed, the friction wheel fits only one specific chain of beads. Therefore, different friction wheels shall be used to fit different sizes of chains of beads.
Further, after a long time of use of the cord-driven rotator, the V-shaped groove or the recessed round holes may become wear, thereby not enabling to hold the lift cord in place.